1. Field of the Invention
The present invention relates to an apparatus for injecting slurry and a method therefor, specifically to the apparatus for injecting slurry capable of suppressing the generation of remained slurry in the injection hole, and to the method for injecting slurry capable of decreasing the amount of the remained slurry and forming the surface of injected slurry in various shapes with high accuracy.
2. Description of the Related Art
Honeycomb filters made of ceramic are used to collect dust and other particulate matter contained in exhaust gas generated from automobile and in incineration flue gas generated during incineration of waste. In particular, a diesel particulate filter (hereinafter referred to from time to time as “DPF”) is used to remove efficiently the particulate matter (hereinafter referred to from time to time as “PM”) such as soot discharged from internal combustion engines.
To increase the collection effect of particulate matter, DPF is normally provided with plugging at one end face and at the other end face of a cell so as to provide a complementary checkered-flag pattern thereon (for example, refer to Japanese Patent Laid-Open No. 2007-296512). That type of plugging is prepared by sticking an adhesive sheet or the like to one end face of the DPF before firing, by applying a mask while opening a hole on the adhesive sheet or the like only at a portion corresponding to the cells to be plugged by laser machining utilizing image processing, or the like, then by immersing the end face in a slurry via the mask, followed by firing the DPF, (for example, refer to Japanese Patent Laid-Open No. 2001-300922).
The depth of slurry being introduced in the cell to be plugged is preferably uniform because the uniform depth allows suppressing the generation of local shrinkage on firing the DPF, thus enabling the DFP to suppress deterioration. To introduce the slurry to cells to be plugged at a uniform depth, it is preferable for the surface of the slurry used for immersion to be formed in a planar state at a certain height.
The surface of the slurry used for immersion, however, was formed in a planar state using a wheel in the related art so that differences in the surface height appeared depending on the skill of the workers. To this point, there has been developed an apparatus for injecting slurry that can form a uniform height of the surface of slurry in a planar state without using wheel.
FIG. 3 is a schematic drawing illustrating an example of the slurry-injected state of an apparatus for injecting slurry in the related art. As shown in FIG. 3, use of an apparatus for injecting slurry 20 very often generated a remained slurry 21 in ejection holes 5. Once that kind of remained slurry 21 is generated, there raises a problem of affecting the physical properties of slurry to deteriorate the DPF on applying the apparatus for injecting slurry in the next operation. Furthermore, since the DPF often gives a difference in pressure loss between the central part and the outer peripheral part thereof, there is a need of manufacturing the DPF having plugging being formed so that the depth of the slurry introduced in the cells may differ between the depth thereof at the central part and the depth thereof at the outer peripheral part. The apparatus for injecting slurry 20 according to the related art, however, was not able to respond to those problems.